Age resistant polymers of 4-(arylamino)aryl esters of α,β unsaturated carboxylic acids

ABSTRACT

Ester age resisters such as 4-anilinophenyl acrylate and 4-anilinophenyl methacrylate, age resistant polymers having ester age resisters physically combined therewith and age resistant polymeric compositions prepared by free radical polymerization techniques involving the use of said esters as monomers.

This invention relates to age resistors, age resistant polymericcompositions and processes for preparing said age resisters and ageresistant compositions. More particularly, the invention relates topolymeric compositions that possess a high degree of resistance to thedeleterious effects of oxidative aging over a prolonged period of timeeven after said compositions have been subjected to solvents which wouldextract a significant portion of many conventional age resisters whenused to stabilize polymeric compositions.

Essentially all types of rubber, both natural and synthetic, andparticularly rubbers formed from dienes, are known to be susceptible todeterioration resulting from prolonged exposure to oxidative aging. Agreat deal of effort has been expended by those engaged in the field ofpolymer technology to develop various stabilizers that will effectivelyinhibit the adverse effects of aging of polymeric compositions.Unfortunately, many of the commercially accepted stabilizers may bevolatilized when the polymeric products are exposed to elevatedtemperatures and/or high vacuum over prolonged periods of time.Furthermore, they are rather quickly extracted from polymericcompositions by repeated washings with aqueous detergent solutions ororganic solvents. These severe conditions are routinely encountered bygarments containing latex treated fabric when they are subjected tofrequent laundering or dry-cleaning.

It is therefore an object of this invention to provide age resisters andpolymeric compositions that are resistant to oxidative aging. It isanother object of this invention to provide a process for preparing ageresistant polymeric compositions. A further object of this invention isto provide polymeric compositions that are highly resistant to oxidativeaging at elevated temperatures even after repeated exposure to aqueousdetergent solutions or dry-cleaning fluids. It is a still further objectof this invention to provide polymers possessing antioxidants chemicallybound thereto.

In accordance with the present invention, age resistant polymericcompositions are prepared by polymerizing certain nitrogen-containingesters by themselves or with one or more comonomers. Thenitrogen-containing esters which can be so used have the followingstructural formula: ##EQU1## wherein R³ is a aryl radical, R and R¹ areselected from the group consisting of hydrogen, alkyl radicals havingfrom 1 to 4 carbon atoms and alkoxy radicals having from 1 to 4 carbonatoms, R² is selected from the group consisting of hydrogen, alkylradicals having from 1 to 4 carbon atoms, alkoxy radicals having from 1to 4 carbon atoms and a radical having the following structural formula:##EQU2## wherein R⁴ is selected from the group consisting of alkylradicals having from 1 to 12 carbon atoms, cycloalkyl radicals havingfrom 5 to 12 carbon atoms, aryl radicals having from 6 to 12 carbonatoms and aralkyl radicals having from 7 to 13 carbon atoms, R⁵ isselected from the group consisting of hydrogen and alkyl radicals havingfrom 1 to 12 carbon atoms and wherein R⁶ and R⁷ are selected from thegroup consisting of hydrogen and alkyl radicals having from 1 to 4carbon atoms, wherein R⁸ is selected from the group consisting ofhydrogen, alkyl radicals having from 1 to 4 carbon atoms, i.e., methyl,ethyl, propyl and butyl radicals; carboxymethyl radical andcarbalkoxymethyl radicals, and R⁹ is selected from the group consistingof hydrogen, alkyl radicals having from 1 to 4 carbon atoms, i.e.,methyl, ethyl, propyl and butyl radicals; phenyl and substituted phenyl,e.g., a phenyl group having located in the para position, an alkylradical having 1 to 4 carbon atoms, such as methyl, or an alkoxy radicalhaving 1 or 2 carbon atoms, e.g., methoxy; carboxyl radical andcarbalkoxy radicals.

Under structural formula (I) the carbalkoxymethyl radicals preferablyhave the following structural formula: ##EQU3## wherein R¹⁰ is an alkylradical having from 1 to 4 carbon atoms. The carbalkoxy radicalspreferably have the following structural formula: ##EQU4## wherein R¹¹is an alkyl radical having from 1 to 4 carbon atoms.

In structural formula (I), R³ preferably is a substituted orunsubstituted phenyl radical, although it may be any other aryl radical,such as a substituted or unsubstituted naphthyl radical. When R² is aradical having the structural formula: ##EQU5## then R² is preferably inthe para position and R³ is preferably a substituted or unsubstitutedphenylene radical. R⁶ and R⁷ are preferably selected from the groupconsisting of hydrogen and methyl. Preferably R⁸ is hydrogen or methyl.Preferably R⁹ is hydrogen. R¹⁰ and R¹¹ in the preferred carbalkoxymethyland carbalkoxy radicals respectively are preferably methyl or ethylradicals.

Representative esters which can be used in the present invention are asfollows:

4-anilinophenyl acrylate

4-anilinophenyl methacrylate

4-anilinophenyl crotonate

4-anilinophenyl cinnamate

4-anilinophenyl hydrogen maleate

4-anilinophenyl hydrogen itaconate

4-anilinophenyl methyl maleate

4-anilinophenyl ethyl itaconate

4-p-toluidinophenyl acrylate

4-p-toluidinophenyl methacrylate

4-o-toluidinophenyl methacrylate

4-(p-methoxyanilino) phenyl acrylate

4-(p-methoxyanilino) phenyl methacrylate

4-(p-ethoxyanilino) phenyl methacrylate

4-(o-methoxyanilino) phenyl methacrylate

4-(2',4'-dimethylanilino) phenyl methacrylate

4-(4'-isopropylanilino) phenyl methacrylate

4-[4'-(N,N-dimethylamino) anilino] phenyl acrylate

4-[4'-(N,N-dimethylamino) anilino] phenyl methacrylate

4-(2'-naphthylamino) phenyl methacrylate

4-(2'-naphthylamino) phenyl acrylate

4-anilino-3-methylphenyl acrylate

4-anilino-2-methylphenyl acrylate

4-anilino-3-methylphenyl methacrylate

4-anilino-2-methylphenyl methacrylate

4-p-toluidino-2-methylphenyl methacrylate

4-(p-methoxyanilino)-3-methylphenyl methacrylate

4-anilino-2,5-dimethylphenyl methacrylate

4-p-toluidinophenyl ethyl maleate

4-(p-ethoxyanilino) phenyl hydrogen maleate

The method of preparing the monomeric age resisters is not critical tothe performance of these compounds in the practice of the presentinvention, although it is preferred that the compound purity be high.

The esters can be prepared by reacting, normally in substantially equalmolar amounts, an alkali metal salt of a phenol of the structure:##EQU6## with an acid halide of the structure: ##EQU7## or with a cyclicacid anhydride selected from the group having the following structuralformulae: ##EQU8## wherein R, R¹, R², R³, R⁶, R⁷, R⁸ and R⁹ are asdefined earlier herein, and wherein X is selected from the groupconsisting of chloride and bromide radicals. Compounds of the presentinvention are produced when the cleavage occurs at the bonds indicatedby the arrows. The reaction is usually carried out by dropwise additionof a solution of the acid halide or anhydride in an aprotic solvent to asolution of the alkali metal salt of the phenol. A slight excess of theacid halide or anhydride may be used. The reaction is usually exothermicbut not to the extent that cooling is necessary. The reaction mixture isstirred for an hour or more after the addition of acid halide oranhydride has been completed. The product may be isolated by pouring thereaction mixture into water, extracting the organic material with awater immercible solvent, removing the solvent, and purifying theresidue as necessary.

Examples of phenols which can be used in preparing the esters are asfollows:

4-anilinophenol

4-p-toluidinophenol

4-o-toluidinophenol

4-(p-methoxyanilino) phenol

4-(p-ethoxyanilino) phenol

4-(o-methoxyanilino) phenol

4-(2',4'-dimethylanilino) phenol

4-(4' -isopropylanilino) phenol

4-[4'-(N,N-dimethylamino)anilino]phenol

4-(2'-naphthylamino) phenol

4-anilino-3-methylphenol

4-anilino-2-methylphenol

4-p-toluidino-2-methylphenol

4-p-methoxyanilino-3-methylphenol

4-anilino-2,5-dimethylphenol

Examples of acid halides which can be used in preparing the esters areas follows:

acryloyl chloride

methacryloyl chloride

crotonyl chloride

cinnamoyl chloride

acryloyl bromide.

Examples of cyclic acid anhydrides which can be used are maleicanhydride, itaconic anhydride, and citraconic anhydride.

The aforementioned monomeric age resisters may be polymerized by wellknown free radical emulsion polymerization techniques with one or morecomonomers that are known to polymerize in free radical initiatedpolymerization systems. Some adjustments in the polymerization recipeand/or conditions may be necessary to obtain a satisfactory rate ofpolymer formation, depending on the amount of monomeric age resisterincluded and the other monomers involved. Adjustments which may benecessary in the polymerization conditions to improve polymerizationrates include increasing the temperature of polymerization and/orincreasng the initiator level and/or increasing the level of activatoringredients. Solvents may also be required to obtain adequate solubilityof the monomers with each other as well as to solubilize otheringredients where required. Some solvents, such as methyl ethyl ketoneor isopropyl alcohol, can be used to advantage with the emulsionpolymerization system. These adjustments, where necessary, are tocounteract the inhibitory effect of the monomeric age resister and toinsure its solubility in the system.

Examples of free radical initiators that are useful in the practice ofthis invention are those known as "Redox" initiators, such asappropriate combinations of chelated iron salts, sodium formaldehydesulfoxylate and organic hydroperoxides such as cumene and paramenthanehydroperoxides. Other initiators such as azoisobutyronitrile, benzoylperoxide, hydrogen peroxide and potassium persulfate may also be used,depending on the particular polymerization recipe.

The monomeric age resisters used in the practice of this invention havecertain chemical characteristics which preclude their use inpolymerization processes other than those initiated by free radicals. By"free radical initiated systems" is meant systems wherein free radicalsare generated by any of various processes such as thermal decompositionof various persulfate, perborate, peroxide, azo or azonitrile compounds;induced (catalytic or "redox" promoted) decomposition of variouspersulfate, peroxide or hydroperoxide compounds and generation of freeradicals by exposure of the system to high energy radiation such asradiation from a radioactive source or ultraviolet light. Such systemsare very well known in the art and are widely used commercially, e.g.,in the preparation of SBR, styrene/butadiene copolymers.

The most widely used system for preparation of elastomeric polymers,i.e., polymers prepared from a monomer charge made up of at least 40weight percent diene, preferably at least 60 weight percent diene, byfree radical initiation is the emulsion system. Polymers ranging all theway from liquid, low molecular weight (molecular weights of about 2,000to 10,000 to polymers of intermediate molecular weight (60,000 to 70,000and higher), to oil extendable, at least 50% soluble, rubbery solid,high molecular weight (100,000 to 500,000 or more) and even highlygelled, less than 50% soluble, may be prepared by emulsionpolymerization. The monomeric age resisters of the present invention canbe used in such emulsion polymerization systems to produce polymers ofthe aforementioned type.

The principles of emulsion polymerization are discussed in referencessuch as "Synthetic Rubber" by G. S. Whitby, Editor-in-Chief, John Wileyand Sons, 1954, particularly Chapter 8, and "Emulsion Polymerization" byF. A. Bovey et al, Vol. IX of "High Polymers", Interscience Publishers,Inc., 1955. Some specialized applications of these principles areindicated in U.S. Pat. Nos. such as 3,080,334; 3,222,334; 3,223,663;3,468,833 and 3,099,650.

Very effective as free radical polymerization initiators used within thepractice of the present invention when used under appropriateconditions, are compounds such as t-butyl hydroperoxide, cumenehydroperoxide, diisopropylbenzene hydroperoxide and paramenthanehydroperoxides, and even hydrogen peroxide. These compounds perform veryeffectively when used in polymerization recipes containing appropriatelevels of supporting ingredients. By "supporting ingredients" is meantthose materials often referred to as activators in emulsion, or othersystems, where required. U.S. Pat. No. 3,080,334 describes some of thesematerials at column 5, lines 20-26. Such materials can also be referredto as catalyst activators. The term "Redox Polymerization" is often usedwhere the complete initiation system includes a Redox system, i.e.,reducing agents and oxidizing agents in a proportion that yieldspolymerization initiating species. All of these initiator systems arewell known in the art.

Emulsion polymerizations are normally accomplished in the range of 5° C.to 90° C. Though the activated or "Redox" initiated systems arepreferred for low temperature polymerizations, they are very effectiveat high temperatures also, normally requiring appreciably lowerquantities of the various ingredients to obtain a desirablepolymerization rate.

The free radical sources used in the initiator systems are thosecustomarily used in free radical polymerizations, for example, organicinitiators such as azo-nitriles, azo-derivatives, peroxides, andhydroperoxides and inorganic initiators such as inorganic peroxycompounds. Radiation, e.g., of the ultraviolet and gamma ray type canalso be used as a free radical source. Various organic initiators aredescribed by J. Brandrup and E. H. Immergut, Polymer Handbook (JohnWiley & Sons), 1965, pages II-3 to II-51. Peroxide initiators includethe aralkyl, aliphatic, aliphatic acyl, aromatic acyl, ketone, aldehydeand perester types. Hydroperoxide compounds include aralkyl andaliphatic hydroperoxides. Inorganic peroxy compounds includepersulfates, perborates, perphosphates and hydrogen peroxide.

Aralkyl peroxides are represented by dicumyl peroxide; aliphaticperoxides by di tert.butyl peroxide; aliphatic acyl peroxides by acetylperoxide, decanoyl peroxide and lauroyl peroxide; aromatic acylperoxides by benzoyl peroxide, and 2,4-dichlorobenzoyl peroxide; ketoneperoxides by methylethyl ketone peroxide and cyclohexanone peroxide;aldehyde peroxides by heptaldehyde peroxide; and perester peroxides bytert.butyl peracetate, tert.butyl perpivalate and tert.butylperbenzoate. Aralkyl hydroperoxides are represented by cumenehydroperoxide and diisopropylbenzene hydroperoxide and aliphatichydroperoxides by tert.butyl hydroperoxide and paramenthanehydroperoxide. Persulfate, perborate and perphosphate compounds arerepresented by the sodium, potassium and ammonium persulfates,perborates and perphosphates; azo-nitriles and azo-derivatives by2,2'-azo-bis-isobutyronitrile, 2,2'-azo-bis-2-methylpropionitrile andazo-bis-diphenylmethane.

Supporting ingredients, i.e. activators capable of activating certaininitiators to produce free radicals include iron compounds such asferrous sulfate or cobalt compounds, complexed with compounds such assodium salts or ethylene diamine tetra acetic acid or sodium orpotassium pyrophosphate. Reducing agents used in Redox systems includesodium formaldehyde sulfoxylate, various sugars and hydrosulfites.

Various initiator system components are described at column 4, lines 14to 32 in U.S. Pat. No. 3,080,334.

Examples of comonomers that can be used with the monomeric antioxidantsof the present invention and that are useful in the practice of thisinvention are polymerizable unsaturated hydrocarbons, both substitutedand unsubstituted, including conjugated diene monomers, such asbutadiene-1,3; 2-chlorobutadiene-1,3; isoprene; 2-ethyl-butadiene-1,3;2,3-dimethyl butadiene- 1,3; piperylene; and hexadienes andcopolymerizable monoolefins including vinyl and vinylidene monomers suchas styrene, alphamethylstyrene, divinyl benzene, vinyl chloride, vinylacetate, vinylidene chloride, methylmethacrylate, ethylacrylate, thevinylpyridines including 2-vinyl pyridene, 5-methyl-2-vinyl pyridine,4-vinyl pyridine and 2-vinyl-5-ethyl pyridine, acrylonitrile,methacrylonitrile, methacrylic acid, acrylic acid and itaconic acid.Mixtures of the monomeric age resisters and mixtures of the comonomersmay be used. The monomer charge weight ratio is normally from about0.10/99.9 to about 10/90 or even 20/80 monomeric age resister/comonomer.The ratio may even be as high as 30/70, or 60/40. A charge ratio ofabout 0.5/99.5 to about 5.0/95 is preferred. Ratios will vary dependingon the amount of age resister desired to be bound and on the reactivityratios of the monomers in the particular polymerization system used.

Preferably the monomer system contains at least 50 parts by weight per100 parts by weight of total monomer of at least one diene, preferably aconjugated diene, such as 1,3-butadiene or isoprene, but always at least40 parts.

One embodiment of the present invention involves the use of a monomersystem comprised of from about 50 to about 99.9 parts of at least onediene monomer, preferably a conjugated diene, 0 to about 49.9 parts ofat least one monomer selected from the group consisting of vinylmonomers and vinylidene monomers and from about 0.10 to about 5.0 partsby weight of at least one monomeric age resister, all parts being byweight per 100 parts by weight of total monomer. Preferably at least 0.5part of monomeric age resister is used. When at least 0.5 part of themonomeric age resister is used, the upper limit on the diene monomerrange is 99.5 parts and the upper limit of the vinyl monomer and/orvinylidene monomer range is 49.5 parts. The upper limit of the monomericage resister range may be even higher than 5.0, i.e., 10, 20, 30 andeven 50.

The polymers resulting from the free radical polymerizations ofmonomeric systems containing the monomeric age resisters of the presentinvention contain segmeric units having the following structures. Wherethe monomeric age resister has a structural formula according to (I) thesegmeric unit has the following structural formula: ##EQU9## wherein R,R¹, R², R³, R⁶, R⁷, R⁸ and R⁹ are as defined in structural formula (I).Preferably the comonomers are selected to produce an elastomericcopolymer.

These polymers, whether liquid or solid, have a special advantage inthat the age resistant portion is not extractable, and, therefore, thepolymeric compositions are highly resistant to oxidative aging evenafter repeated exposure to aqueous detergent solutions or dry-cleaningfluids. This feature is especially significant where polymers are usedin foam backings for rugs and where polymers are used in solution orlatex form to treat fabrics, since such products are often exposed toaqueous detergent solutions or dry-cleaning fluids. This feature is alsosignificant where factors such as contact with lubricating oils orexposure to high vacuum conditions are a consideration.

One of the advantages of the present process is that it permits thepreparation of polymers prepared from monomer systems containing dienemonomers and containing built-in stabilizers, without the formation ofappreciable gel, that is, polymers can be made which are essentiallygel-free. Gel formation is generally undesirable in a polymer since itcan cause processing difficulties and directly and/or indirectly canaffect the physical properties of the polymer in its vulcanized form.Normally a macro gel content of less than 5 percent is desirable.Preferably a gel content of less than 10 percent is desirable. Mostpreferably, a gel content below 5 percent is desirable. Gel is theamount of polymer that is insoluble in an organic solvent such asbenzene. One way to measure gel content is to place about 0.20 to about0.30 grams of the polymer in 100 milliliters of benzene and permit themixture to stand for 48 hours. The mixture is then filtered through a100 mesh stainless steel wire cloth having a wire diameter of 0.045inch. A solids is then run on the filtrate to determine the amount ofsoluble polymer. The amount of gel is the difference between the amountof polymer placed in the benzene originally and the amount of solublepolymer. The percent gel is one hundred times the gel weight divided bythe original polymer weight.

To afford adequate protection against degradation the polymers shouldcontain from about 0.10 part to about 10.0 parts by weight of thesegmeric form of the monomeric age resister per 100 parts by weight ofthe polymer, although from about 0.50 part to about 5.0 parts isnormally satisfactory, from about 0.50 part to about 3.0 parts beingpreferred. As much as 20 parts, 30 parts, 50 parts and more of thepolymer may consist of the age resister segmeric unit, i.e., repeatunit, while the lower limit may be 0.50 part to 0.10 part and lower.However, as the amount of bound age resister increases the physicalcharacteristics of the polymer are altered accordingly. Where it isdesired to produce a polymer which is self-stabilizing and whichsubstantially retains the physical properties of the comonomer orcomonomers, normally the polymer should contain no more than about 10.0parts by weight of the age resister segmeric unit. Such polymerspreferably are elastomeric solids, although they may be liquid. Where itis desired that the polymer act as a polymeric age resister which may beblended with unstabilized polymers, the polymer should normally containgreater amounts of the monomeric age resister. The remainder of thepolymer is comprised preferably of the segmeric form of at least oneconjugated diene monomer and/or the segmeric form of at least one vinylmonomer. Preferably the polymers contain at least 50 percent by weightof the segmeric form of a diene, preferably a conjugated diene such asbutadiene1,3 or isoprene. Most preferred are polymers containing fromabout 50 to about 99.9 parts by weight of the segmeric form of at leastone diene, preferably a conjugated diene, 0 to about 49.9 parts byweight of the segmeric form of at least one monomer selected from thegroup consisting of vinyl monomers and vinylidene monomers and 0.10 to5.0 parts by weight of the segmeric form of at least one monomeric ageresister, all parts being by weight per 100 parts by weight of polymer.Preferably the polymer contains at least 0.5 part of the segmeric formof the monomeric age resister. When the polymer contains at least 0.5part of the segmeric form of the monomeric age resister, the upper limitof diene segmer range is 99.5 parts and the upper limit of the vinylsegmer and/or vinylidene segmer range is 49.5 parts. The upper limit ofthe segmeric form of the monomeric age resister range may be even higherthan 5.0, i.e., 10, 20, 30 and even 50. In all instances the polymersmust contain at least 40 parts by weight of the segmeric form of a dienemonomer, preferably a conjugated diene. In polymers generally preparedby free radical, particularly emulsion techniques, the trans 1,4 contentis generally greater than the cis-1,4 or 1,2 content.

All of the monomeric age resisters described herein are capable ofstabilizing polymers by simple incorporation into the polymers byconventional techniques such as by addition to polymer latices or byaddition to the solid polymer on a mill or in a Banbury. When blending aself-stabilizing polymer with other polymers, especially when theself-stabilizing polymer contains large amounts of the segmeric form ofthe monomeric age resister, one must consider the solubility problemsinvolved in blending dissimilar polymers.

Polymers subject to deterioration by oxidation that can be convenientlyprotected by the age resisters described herein include substituted andunsubstituted, saturated and unsaturated, natural and syntheticpolymers. The oxidizable natural polymers of interest include naturalrubber in its various forms, e.g., pale crepe and smoked sheet, andbalata and gutta percha. The oxidizable synthetic polymers are preparedfrom a single monomer (homopolymer) or a mixture of two or morecopolymerizable monomers (copolymers) wherein the monomers are combinedin a random distribution or block form. The monomers may be substitutedor unsubstituted and may possess one or more double bonds, for example,diene monomers, both conjugated and nonconjugated, and monoolefinsincludng cyclic and acyclic monoolefins, especially vinyl and vinylidenemonomers. Examples of conjugated dienes are 1,3-butadiene, isoprene,chloroprene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene andpiperylene. Examples of non-conjugated dienes are 1,4-pentadiene,1,4-hexadiene, 1,5-hexadiene, dicyclopentadiene, 1,5-cyclooctadiene andethylidene norbornene. Examples of acyclic monoolefins are ethylene,propylene, 1-butene, isobutylene, 1-pentene and 1-hexene. Examples ofcyclic mono-olefins are cyclopentene, cyclohexene, cycloheptene,cyclooctene and 4-methyl-cycloctene. Examples of vinyl monomers arestyrene, acrylonitrile, acrylic acid, ethylacrylate, butylacrylate,methyl vinyl ether, vinyl acetate and vinyl pyridine. Examples ofvinylidene monomers are α-methylstyrene, methacrylic acid, methylmethacrylate, ethylmethacrylate, glycidylmethacrylate and vinylidenechloride. Representative examples of the synthetic polymers used in thepractice of this invention are polychloroprene; homopolymers of aconjugated 1,3-diene such as isoprene and butadiene, and in particular,polyisoprenes and polybutadienes having essentially all of their repeatunits combined in a cis-1,4 structure; copolymers of a conjugated1,3-diene such as isoprene and butadiene with up to 50 percent by weightof at least one copolymerizable monomer including ethylenicallyunsaturated monomers such as styrene or acrylonitrile; butyl rubber,which is a polymerization product of a major proportion of a monoolefinand a minor proportion of a multiolefin such as butadiene or isoprene;polyurethanes containing carbon to carbon double bonds; and polymers andcopolymers of monoolefins containing little or no unsaturation, such aspolyethylene, polypropylene, ethylene propylene copolymers andterpolymers of ethylene, propylene and a nonconjugated diene such asdicyclopentadiene, 1,4-hexadiene, ethylidene norbornene and methylenenorbornene.

When added in free form normally 0.001 to 10.0 percent of the ageresister by weight, i.e., parts by weight based on the weight of thepolymer i.e., 100 parts by weight of the polymer, can be used, althoughthe precise amount of the age-resisters which is to be employed willdepend somewhat on the nature of the polymer and the severity of thedeteriorating conditions to which the polymer is to be exposed. Inunsaturated polymers such as those made from conjugated dienes, theamount of age resister necessary is greater than that required by asaturated polymer such as polyethylene. It has been found that aneffective antioxidant amount of the disclosed stabilizers in rubberyunsaturated polymers will generally range from 0.05 to 5.0 parts byweight per 100 parts by weight of polymer, although it is commonlypreferred to use from 0.5 to 3.0 parts by weight. Mixtures of the ageresisters may be used.

The following examples illustrate the practice of the present invention.Unless otherwise indicated, all parts are parts by weight.

Examples 1 to 5 illustrate the preparation of age resisters which can beused to stabilize polymers by physically combining the polymerstherewith or which can be used in free radical polymerization systems asmonomers to produce self-stabilizing polymers.

EXAMPLE 1

4-Anilinophenylmethacrylate was prepared by adding a solution of 11.5grams of methacryloyl chloride in 50 milliliters of benzene to asolution of the sodium salt of 4-anilinophenol which was prepared bydissolving 18.5 grams of 4-anilinophenol in a solution of 4 grams ofsodium hydroxide in 100 milliliters of ethanol. The addition wasaccomplished in 35 minutes and the reaction mixture was stirred for 1hour. The mixture was then poured into 150 milliliters of water. Theorganic layer was separated, washed four times with 10 percent sodiumhydroxide solution and once with water, dried over anhydrous sodiumsulfate, then allowed to evaporate. The residue was recrystallized fromhexane yielding 11.3 grams of product melting at 72°-73° C.

EXAMPLE 2

4-Anilinophenylacrylate was prepared by adding 10 grams of acryloylchloride to a solution of the potassium salt of 4-anilinophenol whichwas prepared by dissolving 18.5 grams of 4-anilinophenol in a solutionof 3.9 grams of potassium in 75 milliliters of tert.butyl alcohol. Theaddition was accomplished in 12 minutes and the mixture was stirred for2 hours. The reaction mixture was poured into 100 milliliters of waterand the organic layer was separated by extraction with benzene. Thebenzene solution was washed with 5 percent sodium hydroxide solution,washed with water, dried over anhydrous sodium sulfate, then allowed toevaporate. The oily residue is crystallized from hexane yielding 5.3grams of product which melted at 58°-62° C.

EXAMPLE 3

4-Anilinophenyl crotonate was prepared by adding a solution of 11.5grams of crotonyl chloride in 50 milliliters of benzene to a solution ofthe sodium salt of 4-anilinophenol which was prepared by dissolving 18.5grams of 4-anilinophenol in a solution of 4 grams of sodium hydroxide in100 milliliters of ethanol. The addition was accomplished in 30 minutesand the reaction mixture was stirred for 1 hour. The mixture was thenpoured into 150 milliliters of water. The organic layer was separated,washed three times with 10 percent sodium hydroxide solution and oncewith water, dried over anhydrous sodium sulfate, then allowed toevaporate. The residue was recrystallized from hexane yielding 13.3grams of product which melted at 73°-76° C.

EXAMPLE 4

4-Anilinophenyl cinnamate was prepared by adding a solution of 18.2grams of cinnamoyl chloride in 50 milliliters of benzene to a solutionof the sodium salt of 4-anilinophenol which was prepared by dissolving18.5 grams of 4-anilinophenol in a solution of 4 grams of sodiumhydroxide in 100 milliliters of ethanol. The addition was accomplishedin 30 minutes and the reaction mixture was stirred for 1 hour. Themixture was then poured into 150 milliliters of water. The organic layerwas separated, washed three times with 10 percent sodium hydroxidesolution and once with water, dried over anhydrous sodium sulfate, thenallowed to evaporate. The residue was washed with boiling hexane. Therewas obtained 15.0 grams of product which melted at 116°-118° C.

EXAMPLE 5

4-Anilinophenyl hydrogen maleate was prepared by adding 10 grams ofmaleic anhydride to a solution of the potassium salt of 4-anilinophenolwhich was prepared by dissolving 18.5 grams of 4-anilinophenol in asolution of potassium tert.butoxide prepared by reacting 3.9 grams ofpotassium with 75 milliliters of tert.butyl alcohol. The reactionmixture was stirred for 2 hours at 65°-70° C. and was then poured into asolution of 12 milliliters of concentrated hydrochloric acid in 138milliliters of water. The organic layer was separated by extraction withbenzene. The extract was washed twice with water and then allowed toevaporate. The residue was recrystallized twice from benzene yielding1.3 grams of product which melted at 139°-142° C.

The following examples illustrate the preparation of polymers containingmonomeric age resisters as part of the polymeric chain. They alsoillustrate the age resistance possessed by said polymers as well as bypolymers having the monomeric age resisters physically combinedtherewith. Unless otherwise indicated all parts are parts by weight.

EXAMPLE 6

A copolymer of butadiene, styrene and 4-anilinophenyl acrylate wasprepared by polymerizations in 4-ounce bottles using the followingproportions of ingredients.

    __________________________________________________________________________    Order of Addition                                                                          Ingredients        Parts                                         __________________________________________________________________________    3          Butadiene            75.0                                                     Styrene              20.5                                          1          4-anilinophenyl acrylate.sup.(1)                                                                   2.5                                                      Methylethylketone    11.25                                                    Tertiary dodecyl mercaptan                                                                         0.50                                                     Potassium soap of disproportionated                                           rosin acids          2.25                                                     Sodium salt of tallow fatty acids                                                                  2.25                                          2          Tripotassium phosphate                                                                             0.25                                                     Sodium salt of condensed naphthalene                                          sulfonic acid        0.08                                                     Water                190.0                                                    Chelating agent.sup.(2)                                                                            0.074                                                    FeSO.sub.4.7H.sub.2 O                                                                              0.015                                         4          Sodium formaldehyde sulfoxylate                                                                    0.05                                                     Sodium hydrosulfite  0.056                                                    Water                10.0                                          5          Paramenthane hydroperoxide                                                                         0.12                                                     Styrene              4.5                                           __________________________________________________________________________     .sup.(1) The antioxidant monomer was dissolved in methyethylketone before     charging.                                                                     .sup.(2) 90/10 mixture of tetrasodium salt of ethylene diamine tetraaceti     acid and mono-sodium salt of N,N-di(α-hydroxyethyl) glycine.       

The groups of ingredients were added to the 4 ounce bottles in the orderindicated above. The paramenthane hydroperoxide was dissolved in a smallportion of the styrene, about 4.5 parts, while group 4 was added as anaqueous solution in a small portion of the water, about 10 parts.Polymerization was accomplished at 5° C. A conversion of 68 percent wasreached after 16 hours. The polymer was coagulated in 2-propanol andwashed in methanol, then vacuum dried at 60° C.

EXAMPLE 7

Polymerizing in a process similar to that of Example 6 a copolymer ofbutadiene, styrene and 4-anilinophenyl cinnamate was produced. Two andfive-tenths (2.5) parts of the antioxidant monomer were charged. Theproportions of FeSO₄.7H₂ O was reduced to 0.00075 part and theparamenthane hydroperoxide level was adjusted to 0.18 part.Polymerization was accomplished at 25° C. to 28° C. The redoxingredients were charged a second time after 5 hours and a third timeafter 20 hours. Polymerization continued for an additional 24 hoursafter which the polymer was coagulated and washed with methanol andvacuum dried at 80° c.

EXAMPLE 8

Polymerization of butadiene, styrene, and 4-anilinophenyl crotonate wasconducted by a procedure similar to that of Example 6. Before charging,1.25 parts of the antioxidant monomer were combined with the styrene.Sodium sulfate (1.25 parts) was used as the electrolyte in place of themixture of tripotassium phosphate and sodium salt of condensednaphthalene sulfonic acid while the following amounts of redox systemingredients were used.

    ______________________________________                                        Ingredients          Parts                                                    ______________________________________                                        Chelating agent      0.037                                                    FeSO.sub.4.7H.sub.2 O                                                                              0.0075                                                   Sodium formaldehyde sulfoxylate                                                                    0.125                                                    Sodium hydrosulfite  0.028                                                    Paramenthane hydroperoxide                                                                         0.30                                                     ______________________________________                                    

Polymerization was carried out by rotating the charged bottles for 16hours at 50° C. in a water bath. Conversion after this treatment was 81percent. The polymer was obtained by coagulating with methanol. It wasthen washed and dried.

EXAMPLE 9

Polymerization in 4-ounce bottles was accomplished by a procedureexactly like that of Example 8, but with 1.25 parts of 4-anilinophenylmethacrylate as antioxidant monomer. A conversion of 100 percent wasobtained in the 16 hour polymerization time. The polymer was methanolcoagulated and dried.

Table I contains oxygen absorption data for polymers prepared byemulsion polymerization techniques from monomer systems containingmonomeric age resisters of the present invention. The polymerizationswere similar if not identical to those described in Examples 6 to 9.Table II contains oxygen absorption data for SBR-1006 (butadiene/styreneelastomer) containing monomeric age resisters physically incorporatedtherein.

Before oxygen absorption tests were run on the polymers described InTable I, the dry polymers were extracted for 48 hours with methanol in aSoxhlet type apparatus to remove any of the free monomeric age resister,dried again, and then dissolved in benzene. The benzene solutions werepoured into aluminum trays and the solvent was allowed to evaporate. Theresulting films were placed in an oxygen absorption apparatus. Theamount of oxygen absorbed in a particular interval of time wasdetermined and is listed in the following Table I. The testing procedureis described in further detail in Industrial and Engineering Chemistry,Vol. 43, page 456 (1951), and Industrial and Engineering Chemistry, Vol.45, page 392 (1953).

The SBR polymer (1006) in Table II was dissolved in benzene and benzenesolutions of the age resisters were added to portions of the SBRsolutions to provide 1.00 part of the age resisters per 100 parts ofrubbery polymer. The benzene solutions were used to form films andtested in oxygen absorption apparatus as described above.

                                      Table I                                     __________________________________________________________________________    Monomer System (parts)    Hours to 1%                                                                   Oxygen Absorbed                                     Monomeric Age Resister                                                                      Comonomers  at 100° C.                                   __________________________________________________________________________    4-anilinophenyl                                                                acrylate (1.25)                                                                          75/25 butadiene/styrene                                                                     504                                                 4-anilinophenyl                                                                methacrylate (1.25)                                                                      75/25 butadiene/styrene                                                                     516                                                 4-anilinophenyl                                                                crotonate (1.25)                                                                         75/25 butadiene/styrene                                                                     101                                                 4-anilinophenyl                                                                cinnamate (2.5)                                                                          75/25 butadiene/styrene                                                                     577 (0.75%O.sub.2)                                  __________________________________________________________________________    Table II                                                                      __________________________________________________________________________    SBR-1006                                                                                              Hours to 1% Oxygen                                        Antioxidant         Absorbed at 100° C.                            __________________________________________________________________________    4-anilinophenyl acrylate (1.0 parts)                                                                  554                                                   4-anilinophenyl hydrogen maleate (1.0 parts)                                                          648                                                   __________________________________________________________________________

The above data demonstrate that the monomeric age resisters describedherein are capable of providing age resistant polymeric compositions byeither polymerizing the monomeric age resister in an emulsion-freeradical polymerization system along with comonomers or by incorporatingthe monomeric age resisters by conventional techniques into thepolymers. That is, the age resisters provide protection whether in afree or bound condition. Any of the monomeric age resisters, comonomers,initiator systems or polymers described earlier herein can besubstituted for their counterparts in the above working examples toprovide age resistant polymeric compositions. Naturally certain changesin variables such as the emulsification system to be used may benecessary as a result of the use of different monomers. However, suchchanges would be routine to those skilled in the art.

For example, in Examples 6 to 9 isoprene could have been substituted forall or part of the butadiene. Likewise, vinylidene chloride could havebeen substituted for all or part of the styrene or acrylonitrile used insaid examples. 4-p-Toluidinophenyl acrylate or 4-(p-methoxy anilino)phenyl acrylate could have been substituted for any of the monomeric ageresisters described in any of said examples.

All of the polymers prepared in Examples 6 to 9 were solid elastomers.

Naturally polymerization rates and amounts of bound monomer can vary, aswell as the type of emulsifier to be used, depending upon the monomersused. Also, reactor size and degree of agitation can affectpolymerization rates. However, optimum conditions and systems can bedetermined based upon the above revelations by routine experimentationby one possessing ordinary skill in the art.

All polymer molecular weights referred to herein, unless otherwiseindicated, are number average molecular weights.

The age resistant polymeric compositions prepared by chemically bindingthe age resisters or by physically incorporating them into polymers, areage resistant, whether in vulcanized or unvulcanized form. They may beused, depending on the particular polymer involved, in products such astires, industrial rubber products, such as transmission belts and hose,and molded goods. Where the polymeric composition contains the ageresister as an integral part of the polymer chain, it is especiallyuseful in applications where a product is frequently exposed to aqueousdetergent solutions or dry-cleaning fluids, for example, in foambackings for rugs and in polymer treated fabrics.

Polymerization rates can often be improved by using a purified monomericage resister and/or by raising the polymerization temperature, usingmore potent initiator systems, increasing the initiator level or by anyof the conventional means of improving polymerization rates.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:
 1. A process of preparing an age resistant polymeric composition comprising polymerizing in an emulsion free radical polymerization system, a monomer system containing at least one monomeric age resister having the following structural formula: ##EQU10## wherein R³ is an aryl radical, R and R¹ are selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms and alkoxy radicals having from 1 to 4 carbon atoms, R² is selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms, alkoxy radicals having from 1 to 4 carbon atoms and a radical having the following structural formula: ##EQU11## wherein R⁴ is selected from the group consisting of alkyl radicals having from 1 to 12 carbon atoms, cycloalkyl radicals having from 5 to 12 carbon atoms, aryl radicals having from 6 to 12 carbon atoms and aralkyl radicals having from 7 to 13 carbon atoms, R⁵ is selected from the group consisting of hydrogen and alkyl radicals having from 1 to 12 carbon atoms and wherein R⁶ and R⁷ are selected from the group consisting of hydrogen and alkyl radicals having from 1 to 4 carbon atoms, wherein R⁸ is selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms, carboxymethyl radical and carbalkoxymethyl radicals and R⁹ is selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms, phenyl and substituted phenyl, carboxyl radical and carbalkoxy radicals and wherein the monomer system contains at least 40 parts by weight of diene monomer per 100 parts by weight of total monomer in the monomer system.
 2. The process according to claim 1 wherein the diene monomer is a conjugated diene monomer.
 3. The process according to claim 2 wherein the diene monomer is a conjugated 1,3-diene monomer.
 4. The process according to claim 3 wherein the monomer system contains 0.10 to 10.0 parts by weight of at least one monomeric age resistor per 100 parts by weight of total monomer.
 5. The process according to claim 1 wherein the monomer system is comprised of from 50 to 99.9 parts of at least one conjugated diene monomer, 0 to 49.9 parts of at least one compound selected from that group consisting of vinyl monomers and vinylidiene monomers and 0.10 to 10.0 parts by weight of at least one monomeric age resister according to claim 1, all parts being by weight per 100 parts by weight of total monomer.
 6. The process according to claim 1 wherein R⁸ is selected from the group consisting of hydrogen, methyl, a carboxymethyl radical and carbalkoxymethyl radicals having the following structural formula: ##EQU12## wherein R¹⁰ is an alkyl radical having from 1 to 4 carbon atoms, wherein R⁹ is selected from the group consisting of hydrogen, phenyl, a carboxyl radical and carbalkoxy radicals having the following structural formula: ##EQU13## wherein R¹¹ is an alkyl radical having from 1 to 4 carbon atoms.
 7. The process according to claim 6 wherein R⁶ and R⁷ are selected from the group consisting of hydrogen and methyl.
 8. The process according to claim 7 wherein R³ is selected from the group consisting of substituted and unsubstituted phenyl radicals.
 9. The process according to claim 1 wherein R² is in the para position and has the following structural formula ##EQU14## and wherein R³ is selected from the group consisting of substituted and unsubstituted phenylene radicals.
 10. The process according to claim 8 wherein R⁸ is selected from the group consisting of hydrogen and methyl and R⁹ is hydrogen.
 11. The process according to claim 6 wherein R¹⁰ and R¹¹ are selected from the group consisting of methyl and ethyl radicals.
 12. The process according to claim 6 wherein the diene monomer is a conjugated 1,3-diene monomer.
 13. The process according to claim 1 wherein the monomeric age resister is selected from the group consisting of 4-anilinophenyl acrylate and 4-anilinophenyl methacrylate.
 14. A polymer containing segmeric units, at least a portion of said units being comprised of at least one of the age resistant segmeric entities selected from the group consisting of those having the following structural formulae: ##EQU15## wherein R³ is an aryl radical, R and R¹ are selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms and alkoxy radicals having from 1 to 4 carbon atoms, R² is selected from the group consisting of hydrogen, alkyl radicals having from 1 to 4 carbon atoms, alkoxy radicals having from 1 to 4 carbon atoms and a radical having the following structural formula: ##EQU16## wherein R⁴ is selected from the group consisting of alkyl radicals having from 1 to 12 carbon atoms, cycloalkyl radicals having from 5 to 12 carbon atoms, aryl radicals having from 6 to 12 carbon atoms and aralkyl radicals having from 7 to 13 carbon atoms, R⁵ is selected from the group consisting of hydrogen and alkyl radicals having from 1 to 12 carbon atoms and wherein R⁶ and R⁷ are selected from the group consisting of hydrogen and alkyl radicals having from 1 to 4 carbon atoms, wherein R⁸ is selected from the group consisting of hydrogen; alkyl radicals having from 1 to 4 carbon atoms; carboxymethyl radical and carbalkoxymethyl radicals and R⁹ is selected from the group consisting of hydrogen; alkyl radicals having from 1 to 4 carbon atoms; phenyl and substituted phenyl; carboxyl radical and carbalkoxy radicals, and wherein the polymer contains at least 40 parts by weight of the segmeric form of a diene monomer per 100 parts by weight of the polymer.
 15. The polymer according to claim 14 wherein the age resistant segmeric entity comprises 0.10 part to 10.0 parts by weight per 100 parts by weight of the polymer.
 16. The polymer according to claim 14 wherein the segmeric form of the diene monomer is present at a level of at least 50 parts by weight per 100 parts by weight of the polymer and wherein the diene monomer is a conjugated 1,3-diene monomer.
 17. The polymer according to claim 16 wherein the polymer is a solid.
 18. The polymer according to claim 17 wherein the polymer contains from 0.10 part to 10.0 parts by weight per 100 parts by weight of polymer of the age resistant segmeric unit and correspondingly 90 parts to 99.9 parts by weight of at least one segmeric form of at least one comonomer selected from the group consisting of conjugated 1,3-diene monomers, vinyl monomers and vinylidene monomers with the proviso that at least 50 parts by weight of the polymer is the segmeric form of a conjugated 1,3-diene monomer.
 19. The polymer according to claim 18 wherein the polymer contains at least 50 percent by weight of at least one segmeric form of 1,3-butadiene.
 20. The polymer according to claim 14 wherein the polymer contains 50 to 99.9 parts by weight of the segmeric form of at least one diene monomer, 0 to 49.9 parts by weight of at least one compound selected from the group consisting of vinyl monomers and vinylidene monomers and 0.10 to 5.0 parts by weight of at least one monomeric age resister, all parts being by weight per 100 parts by weight of polymer.
 21. The polymer according to claim 17 wherein the polymer possesses a number average molecular weight of from 60,000 to 500,000.
 22. The polymer according to claim 17 wherein the polymer possesses a number average molecular weight of at least 60,000 and has a macro gel content of less than 50 percent.
 23. The polymer according to claim 18 wherein R⁸ is selected from the group consisting of hydrogen, methyl, a carboxymethyl radical and carbalkoxymethyl radicals having the following structural formula: ##EQU17## wherein R¹⁰ is an alkyl radical having from 1 to 4 carbon atoms, wherein R⁹ is selected from the group consisting of hydrogen, phenyl, a carboxyl radical and carbalkoxy radicals having the following structural formula: ##EQU18## wherein R¹¹ is an alkyl radical having from 1 to 4 carbon atoms.
 24. The polymer according to claim 23 wherein R¹⁰ and R¹¹ are selected from the group consisting of methyl and ethyl radicals.
 25. The polymer according to claim 24 wherein the polymer contains at least 50 percent by weight of at least one segmeric form of 1,3-butadiene.
 26. The polymer according to claim 14 wherein the macro-gel content is less than ten percent. 